combine.c (make_extraction): Correct offset computation.

	* combine.c (make_extraction): Correct offset computation.
	* gcc.c-torture/execute/20051012-1.c: New test.

From-SVN: r105330

gcc/ChangeLog

+2005-10-12  Adrian Straetling <straetling@de.ibm.com>
+
+	* combine.c (make_extraction): Correct offset computation.
+
 2005-10-12  Hans-Peter Nilsson  <hp@axis.com>
 
 	* config/cris/t-linux (LIMITS_H_TEST): Define.

gcc/combine.c

@@ -6512,11 +6512,12 @@ make_extraction (enum machine_mode mode, rtx inner, HOST_WIDE_INT pos,
 	offset -= GET_MODE_SIZE (is_mode) - GET_MODE_SIZE (inner_mode);
 
       /* If this is a constant position, we can move to the desired byte.
-	 Be careful not to go beyond the original object. */
+	 Be careful not to go beyond the original object and maintain the
+	 natural alignment of the memory.  */ 
       if (pos_rtx == 0)
 	{
 	  enum machine_mode bfmode = smallest_mode_for_size (len, MODE_INT);
-	  offset += pos / GET_MODE_BITSIZE (bfmode);
+	  offset += (pos / GET_MODE_BITSIZE (bfmode)) * GET_MODE_SIZE (bfmode);
 	  pos %= GET_MODE_BITSIZE (bfmode);
 	}
 

gcc/testsuite/ChangeLog

+2005-10-12  Adrian Straetling <straetling@de.ibm.com>
+
+	* gcc.c-torture/execute/20051012-1.c: New test.
+
 2005-10-12  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/18082

gcc/testsuite/gcc.c-torture/execute/20051012-1.c

+extern void abort (void);
+
+struct type 
+{
+  int *a;
+  
+  int b:16;
+  unsigned int p:9;
+} t;
+
+unsigned int 
+foo ()
+{
+  return t.p;
+}
+
+int 
+main (void)
+{
+  t.p = 8;
+  if (foo (t) != 8)
+    abort ();
+  return 0;
+}